Do I need to cut back on the watering and fertilizing of my mandevilla that I have brought inside for the winter as a houseplant? Presently, I have it in a south-facing bedroom window with sun coming through the window, but I have the plant about three feet back from window and behind other plants. It does get some direct sun, as the window is 54 inches wide and high. It is growing profusely and is a beautiful plant, but the bottom leaves seem to be turning yellow and falling off. Should I trim off the vining shoots, as there are lots of them? This is in a large 24-inch pot, and this is the second year I have had it. Of course, last year I had no problem because it was still small. It did bloom with one flower since I have had it indoors. Last spring I set it back outdoors in May and it was loaded with blooms all summer and still fully in bloom when I brought it back indoors.
Keeping Mandevilla Alive Indoors in Winter
Certified GKH Gardening Expert
Yellowing leaves on a plant that is indoors for the winter are usually either because of the lower sunlight or because of overwatering. Check whether the soil surface is dry or almost dry before watering. Plants also shouldn't be fertilized during the winter, because they will usually be growing more slowly. Other possibilities include pest issues, as described here:
Other than that, it sounds like your plant is doing well. You can prune back the vining shoots any time.